Excess nitrogen from agricultural and urban lands is contaminating groundwater, streams, lakes and estuaries, where it causes harmful algal blooms and contributes to fish kills.
Cost-effective approaches to removing this nitrogen from croplands and urban stormwater runoff before it reaches sensitive water bodies have been elusive.
But simple and inexpensive technologies are on the horizon. A recent scientific workshop on denitrification brought together ecologists, engineers and policy experts to find answers.
Denitrification is a biological process carried out by soil and aquatic microorganisms, in which forms of reactive nitrogen are converted to unreactive and harmless dinitrogen gas.
Findings from the workshop, held in May, 2009, at the University of Rhode Island, are published in the November, 2010, special issue of the scientific journal Ecological Engineering.
The workshop was sponsored by the National Science Foundation (NSF)'s Denitrification Research Coordination Network (RCN), established to enhance collaboration among researchers investigating denitrification.
"This special issue of Ecological Engineering, with its focus on managing denitrification in human-dominated landscapes, highlights our need to understand Earth's microorganisms and their processes," says Matt Kane, program director in NSF's Division of Environmental Biology, which funded the RCN and the workshop.
"The RCN brought together an international and interdisciplinary group of scientists and engineers to synthesize the knowledge necessary to provide pure water for generations to come."
At the workshop, more than 40 participants combined their expertise to address the goal of using ecological principles in engineering design to control nitrogen pollution.
One workshop goal was to evaluate a new and relatively inexpensive way to treat wastewater and drainage from agricultural lands using "denitrifying bioreactors."
These bioreactors use common waste products, such as wood chips, to provide a food source for naturally occurring microorganisms. The microbes convert dissolved nitrogen into harmless nitrogen gas, which is then released to the atmosphere.
Research results in Ecological Engineering are reported from New Zealand, Canada and several locations in the United States.
All confirm that denitrifying bioreactors may be used in many settings, and operate well in a range of temperatures.
The systems have been successful in the cleanup of domestic effluent from small townships, septic tank systems and wastes from dairy farms, says Louis Schipper of the University of Waikato, New Zealand, author of the lead paper in the journal.
"Denitrifying bioreactors have been integrated into agricultural fields," adds Eric Davidson of The Woods Hole Research Center in Falmouth, Mass., and co-author of the journal's lead paper.
"Underground drainage pipes there remove excess water that contains excess nitrogen. By intercepting some of this drainage water, direct inputs of nitrate to surface water can be reduced."
The largest bioreactor tested, by Schipper and colleagues Stewart Cameron and Soren Warneke at the University of Waikato, is 200 meters long by five meters wide by two meters deep. It treats effluent from greenhouse-grown tomatoes.
Research led by Will Robertson of the University of Waterloo found that bioreactors may operate for more than a decade without replacement of wood chips or substantive maintenance.
Similar longevity was confirmed in research in Iowa by Tom Moorman of the USDA-Agricultural Research Service.
Studies by D.Q. Kellogg and Art Gold of the University of Rhode Island demonstrate that recent advances in geospatial data--such as computer-based maps of geologic and land-use patterns--provide a decision-support tool for local regulatory and planning agencies.
These advances, Kellogg and Gold say, will help reduce nitrate-loading to downstream waters.
A study conducted at the University of California at Davis by Harold Leverenz and reported in the journal showed that plants may be grown on the surface of denitrifying bioreactors, providing biodiversity benefits.
"Research presented in this special issue of Ecological Engineering goes a long way toward applying a scientific understanding of the biological processes of denitrification to the engineering challenges of denitrifying bioreactors," says Davidson.
"The resulting guidelines and principles for denitrifying bioreactor design and operation are an additional option in the land manager's tool box."
Cheryl Dybas | EurekAlert!
International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
World Water Day 2017: It doesn’t Always Have to Be Drinking Water – Using Wastewater as a Resource
17.03.2017 | ISOE - Institut für sozial-ökologische Forschung
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy